Repeating coil



Aw. L., CASPER REPATING COIL l im@ 15,1927. 1,617,372

-I-Tiled June 1l. 1921 fy/ A OOOOOOOOO 35i inner layers adjacent theouter layers of said WILLIAM L. CASPER, DE' BRQOKLYN, NEW YRK, ASSGNORT0 WESTERN' ELECTC COMPANY, INCRPOETED, DI?? NEW "YQEK, N. Y., ACORPORATION 0F NEW YORK.

REPEATEG COIL.

Application-med June 11, 1921. Serial No. 476,676.

. This invention relates to transmission circuitsand pertains moreespecially to a speech transmission circuit in which there is providedan input transformer for a vacuum tube repeater, the cathode of which isgrounded, as is usual in telephonie circuits. The transformers usuallyemployed in such circuits are composed of multi-layer coaxial coilswhich are so arranged that ,the lcapacities between the coils andthecore' or between the coils and the casing are practically negligible,whereas the capacities bef 4tween the adjacent la ers of the superposedcoils have considerab y larger values which can not be neglected.

It is the object of this invention to materially reduce in such acircuit the eii'ect of the capacity between the primary and secondarywindings of the transformer. This object is accomplished-by connectingthe grid of the associated vacuum tube to a layer of the secondarynon-adjacent to the primary and the orrounded cathode of the tubeA to alayer of the secondary adjacent the primary.

The invention will be better understood by having reference to thefollowing speciication and accompanying drawinguwherein F ig. 1discloses the winding of the transformer and its connections and Fig. 2is a diagrammatic representation thereof.

In one embodiment, the transformer com-A prises a substantiallyrectangular trame 1 y around the ends 2 and 3 of which are Wound A themulti-layer primary coils 4 and 5. Surrounding the coils 4 and 5 andhaving their coils are the multi-layer secondary` coils 6 and 7 whichcooperate with the coils 4 and 5 to form the rimary and secondary ot'the transformer. Ilinding posts 8, 9, 10 and 11 are provided for theinner and-outer layers of the primary coils 4 and 5. The inner and outerlayers of the secondary coils 6 and Y are provided withv thebinding'posts 12, 13, 14 and 15. The binding posts 8 and 11 areconnected to the incoming line and a conductor 16 connects the bindingposts -9 ad l0. The conductor 16, by virtue ot its symmetrical positionwith respect. to the incoming line of the circuit is maintainedatlefiective ground potential because of the capacities to gr ing line.The binding posts 13 and 14 of ound of the two members of the incomthesecondary coils are connected by a conductor 18, the binding post 12with ythe grid 19 of a vacuum tube 20 and the binding post`15 with thecathode 21 of said tube, said connection 4being grounded at 22.' Theanode 23 and the'cathode 21 of the .tube are connected .with the outputside of the circuit in the usual Way,

Fig. 2 discloses diagrammatically the effeet ofithis method ofconnection upon the capacities between the adjacent 'layers of theprimary and secondary coils. Those portions of the coils adjacent thebinding posts 8, 10, 12 and 14 represent the outer layers of the coils4, 5, 6 `and 7, respectively, and those vportions adjacent the bindingposts 9, 11, 13 and 15 represent the inner layers of said coils 4, 5, 6and 7, respectively. The capacities A and B are, therefore, convenientlyrepresented as being vbetween the outer end of coil 4 and the inner end.of coil 6v and between the outer end of coil 5 and the inner end vofcoil 7 respectively.l

The ratio of the impedance of the primary coil 4, in a commercialembodimentl of this invention, to that of the secondary is approximatelyone to a thousand,'and thereiore the primary coil 4 may, for allpracaian.

tical purposes, be considered merely as a plate. rl`he capacity Aconsequently has practically the same effect as if it were bet-Ween theinner end otcoil 6 and the member 16 of ground potential and is, due tothe ground connection A22, inelect shouted around the coil 7. Since theterminals 10 and 15 of the capacity B are connected to ground potentialmember 16 and to the ground 22 respectively, the eii'ect thereof isnullified. The single effective capacity A can shunt out only a Verysmall portion of the incoming potentials ot the higher frequencies andthe circuit 'is therefore capable ot' high quality speech transmission.

Although the transformer sections are disclosed as 'being wound aroundthe ends of a rectangular frame, this construction being known as coretype, it is to be understood.

that they may be arranged upon a central limb of vthe core in axialalinement, Which construction is known as shell type. Furthermore,although each oi the primary fand secondary .windings arel heredisclosed as comprising a pair of sections, itis within Cil the spiritof this invention to compose .either ot' Said windings of a singlesection or ot several sections.

vWhat is claimed is:

l. In con'ihination in an electrical system, an electric device havinganormally grounded element, a line`r and a transformer tor connectingsaid liiie Ato `said device, said transv former having superposedprimary and secondary windings, the priniary windingy being connected tosaid line, said secondary winding comiirising a plurality of superposedlayers, the layer thereof adjacent said primary winding:r beingconnected to the grounded element of said'eicctric device.

A2. lhe combination, as claimed in claim l, in which'said 4electricdevice comprises a space discharge device 'having a grounded cathode,and agrid, the layer of said seco1odary winding which isnon-adjacei'itsaid primary winding being connected to said grid.

3. A incoming line having its two sides balanced with respect to ground,a vacuum tube repeater having a cathode, a grid and an anode,v atransformer 'tor connectingI Said line to the input of said vacuum tuhe,said transformer comprising sections each consisting of primary andsecondary windings, the windings within each section being in superposedlayers and connections between the sections oi' the respective windingsand from thewiruling terminals to said line and said vacuum tuhe`respectively, such that in each section of the secondary winding thecircuit leading troni the grrid passes first to the layer most remotefrom the primary Winding while the circuit leadinga from the cathodepasses first to the layer adjacent the prin'iary winding, and aconnection from said cathode to 2ground.

4.. The method oi reducing;1 the eiiective shunt capacity of a step-uptransformer for the input circuit. ot a vacuum tube repeater,connirising disposing the secondary winding in a plurality oi sectionsconnected in series with one another whereby the turnwinding is reduced,and reducing the shunt transmission circuit comprising an *to-turn shuntcapacity of the Msecondarying eti'ect of the capacity between windingsby connecting the grid and cathode leads so that the lead from. the gridpasses irst t0 the .layer in each section ot the secondary winding thatis most remote trom the primary while the lead trein the cathode passeslires; to the layer of the secondary, in each section, that adjacent theprimary,

it transmission circuit Acomprising a line balanced with" respect toground, a vacuum tuhe having a grid and a grounded cathode, and atransformer having a pri- ,mary winding;r connected to said line and aminal most remote i'iom thc primary wind yingr to the grid. und aconnection from the secondaryv windingl terminal adjacent said primaryywinding to said cathode.'

t?. ln a transmission circuit7 an incoming line having its' terinii'ialssubstantially lialauced with respect to ground, a transformer having` apair ot' multi-layer primary windings, a-connection from the outer layerot' one ot said wiiu'lii'ios to one terminal ot the other of saidwindings7 connections he* tween the other terminals of said windings andthe terminals oi said line, a pair ot multilayer secondary windings torsaid tra nsformcr surrounding said 'prin'iary windings, a vacuum tuhchaving e'cathode and a grid, a connection from the inner layer oi thesecondary winding` surrounding tlu` first mentioned primary and thecathode ol' tintuhc, a connection trom the outer layer oi' llu othersecondary Windingr to the grid of the tuhc, and a connection trom thecathode ol the tube to ground.

n witne s' whereof. l hereunto subscribe my neme this itlth dar of Juneit. iJzL WLLIA iri ii, CASPER.

